Specialized Metabolites in Biological Systems (Part II ): Focus on Volatile Metabolites in Human and Microbial Studies

Volatile organic compounds (VOCs) released by the human body result from endogenous metabolism, microbial activity, and environmental exposures. As volatile markers, they offer noninvasive access to information on physiological and pathological states. This chapter provides an integrative overview of human volatilomics, examining the biochemical origins of VOCs, the main analytical approaches used for their detection, and the interpretive challenges involved. The discussion is organized across five biological matrices (breath, skin, blood, urine, and stool), highlighting how each reflects distinct metabolic processes. Particular attention is given to high-resolution techniques, such as GC-MS and GC×GC-MS, which enable reliable detection and structural elucidation of trace-level compounds. in vitro and ex vivo models are also considered for investigating VOC formation under controlled conditions. The chapter underscores the need for standardization, cautious interpretation, and stronger integration between analytical data and biological context, positioning volatilomics as a promising yet still developing approach in human biomonitoring.